Preheat the oven to 350°F (175°C) and line a 12-cup cupcake pan with liners.
In a bowl, mix together the milk and lemon juice. Let it sit for 5 minutes, then add light brown sugar, castor sugar, oil, and vanilla extract. Stir until the sugar is almost dissolved.
Combine all the dry ingredients (flour, cocoa powder, baking soda, baking powder, salt) & mix until combined.
Add dry mix to wet ingredients. Stir well.
Add Freshly brewed coffee or boiling water, mix until combined and batter is smooth.
Fill each cupcake liner about 3/4 of the way with the batter.
Bake in the preheated oven for 13-15 minutes or until the cupcakes are firm to the touch and a toothpick inserted into the center comes out clean.